CN115579926A - Energy storage system and control method thereof - Google Patents
Energy storage system and control method thereof Download PDFInfo
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- CN115579926A CN115579926A CN202211340874.2A CN202211340874A CN115579926A CN 115579926 A CN115579926 A CN 115579926A CN 202211340874 A CN202211340874 A CN 202211340874A CN 115579926 A CN115579926 A CN 115579926A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
- H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses an energy storage system and a control method thereof. The energy storage system comprises an inverter grid-connected control loop and a photovoltaic direct-current converter control loop, wherein a first battery voltage upper limit amplitude limiting loop and a battery voltage lower limit amplitude limiting loop are arranged on the inverter grid-connected control loop, and a second battery voltage upper limit amplitude limiting loop and a bus voltage upper limit amplitude limiting loop are arranged on the photovoltaic direct-current converter control loop; the method comprises the steps of automatically switching a first battery voltage upper limit amplitude limiting loop, a battery voltage lower limit amplitude limiting loop, a second battery voltage upper limit amplitude limiting loop and a bus voltage upper limit amplitude limiting loop according to the operation mode judgment and detection results of an energy storage system by detecting the upper limit and the lower limit of the battery voltage and the upper limit of the bus voltage, and adjusting the output power of an inverter and a photovoltaic direct current converter according to the loop results. The invention automatically adjusts the power control of the inverter and the photovoltaic direct current converter by adding an additional control constraint loop.
Description
Technical Field
The invention relates to the technical field of electrochemical energy storage, in particular to an energy storage system and a control method thereof.
Background
Generally, the energy storage system topology is shown in fig. 1, and mainly includes 0 or one or more photovoltaic dc converters 102,0 or one or more battery dc converters 103, and an inverter 104, wherein the front-end input of the photovoltaic dc converter 102 is a photovoltaic battery 106, the front-end input of the battery dc converter 103 is a battery 107, the outputs of the photovoltaic dc converter 102 and the battery dc converter 103 are connected together to the input of the inverter 104, and the output of the inverter 104 is connected to the grid 105 and the load 108. When the number of the photovoltaic direct current converters 102 is 0, the system is not connected with the photovoltaic battery 106, and when the number of the battery direct current converters 103 is 0, the battery 107 is directly connected to the input end of the inverter 104. When the voltage of the power grid is normal, the system is in grid-connected operation, and when the voltage of the power grid is abnormal, the system is switched to off-grid operation. When the system works, the battery direct current converter 103 controls the bus voltage of the output end to be a constant value, the inverter 104 performs power control according to the power set of the dispatching system, and the photovoltaic direct current converter 102 performs power control according to the maximum power point of the photovoltaic battery 106. According to the power balance, there is a photovoltaic dc converter total output power 110+ a battery dc converter total output power 111= an inverter output power 112.
In the existing energy storage system control method, because an inverter needs to respond to a power instruction of a dispatching system to enable a battery direct-current converter to stabilize bus voltage, a special control link is not provided to directly control the battery voltage and the battery power, and when the battery power exceeds a certain value, the photovoltaic power subtracts the battery power to obtain the given output power of the inverter through a power balance formula to control; when the battery voltage exceeds a certain value, the inverter power command value is linearly attenuated, and the output power of the photovoltaic direct-current converter is controlled through a power balance formula. The method has certain hysteresis for controlling the voltage of the battery and the charging and discharging power of the battery, and when the power response and the power control precision of the inverter and the photovoltaic direct-current converter are insufficient, the safety performance of the battery is influenced.
Based on the defects of the control method, the energy storage system and the control method thereof are necessarily developed, starting from the control loop of the inverter and the photovoltaic direct current converter, the power control of the inverter and the photovoltaic direct current converter is automatically adjusted by adding an additional control constraint loop, the problems of power distribution and safety constraint among power modules of the energy storage system are solved, and the control constraint loop replaces the power balance calculation of the system, so that the dynamic response speed of the system is improved, and the complexity of the control logic of the system is reduced.
Disclosure of Invention
The invention aims to provide an energy storage system and a control method thereof, so as to overcome the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the energy storage system comprises an inverter grid-connected control loop and a photovoltaic direct-current converter control loop, wherein the inverter grid-connected control loop is provided with a first battery voltage upper limit amplitude limiting loop and a battery voltage lower limit amplitude limiting loop, and the photovoltaic direct-current converter control loop is provided with a second battery voltage upper limit amplitude limiting loop and a bus voltage upper limit amplitude limiting loop; the method comprises the steps of automatically switching a first battery voltage upper limit amplitude limiting loop, a battery voltage lower limit amplitude limiting loop, a second battery voltage upper limit amplitude limiting loop and a bus voltage upper limit amplitude limiting loop according to the operation mode judgment and detection results of an energy storage system by detecting the upper limit and the lower limit of the battery voltage and the upper limit of the bus voltage, and adjusting the output power of an inverter and a photovoltaic direct current converter according to the loop results.
The invention also provides a control method of the energy storage system, which comprises the following steps,
step S301, judging the operation mode of the energy storage system;
step S302, if the operation mode of the energy storage system is grid-connected operation, step S303 is executed;
step S303, the energy storage system judges whether the battery voltage is limited to the upper limit, if so, step S304 is executed, otherwise, step S309 is executed;
step S304, triggering a first battery voltage upper limit amplitude limiting loop to automatically take effect;
step S305, the first battery voltage upper limit amplitude limiting loop controls the battery voltage within the upper limit amplitude limit by increasing the discharge power of the inverter or decreasing the charge power of the inverter;
step S306, the energy storage system judges the upper limit of the limiting value of the trigger power of the inverter;
step S307, triggering a second battery voltage upper limit amplitude limiting loop to automatically take effect;
step S308, the second battery voltage upper limit amplitude limiting loop controls the battery voltage within the upper limit amplitude limit by reducing the output power of the photovoltaic direct current converter;
step S309, the energy storage system judges that the battery voltage reaches a lower limit amplitude limit;
step S310, triggering a battery voltage lower limit limiting loop to take effect;
step S311, the battery voltage lower limit amplitude limiting loop controls the battery voltage above the lower limit amplitude limit by reducing the discharge power of the inverter or increasing the charging power of the inverter;
step S312, if the operation mode of the energy storage system is off-grid operation, executing step S313;
step S314, triggering the second battery voltage upper limit amplitude limiting loop to automatically take effect;
step S315, the second battery voltage upper limit amplitude limiting loop controls the battery voltage within the upper limit amplitude limit by reducing the output power of the photovoltaic direct current converter;
step S316, the energy storage system judges that the bus voltage exceeds a control value;
step S317, triggering the bus voltage upper limit amplitude limiting loop to automatically take effect;
in step S318, the bus voltage upper limit limiting loop controls the bus voltage within the upper limit limiting by reducing the output power of the photovoltaic dc converter.
Further, the working process of the first battery voltage upper limit limiting loop is as follows: and the difference between the upper limit amplitude limit UbatUpLimit of the battery voltage and the corresponding battery voltage feedback value UbatFb is sent to the PI controller, and the output of the PI controller is subjected to an amplitude limiting loop and is inverted to be used as the adjustment quantity delta PinvRef2 of the output power of the inverter.
Further, the working process of the battery voltage lower limit limiting loop is as follows: and the battery voltage lower limit amplitude limiting UbatDpLimit and the corresponding battery voltage feedback value UbatFb are subjected to difference and then are sent to the PI controller, and the output of the PI controller is subjected to an amplitude limiting loop and is inverted to be used as the adjustment quantity delta Pinv _ ref1 of the output power of the inverter.
Further, the step S306 specifically includes: when the inverter detects that the total power given by PinvRef of the inverter is equal to the upper limit amplitude of the power limit amplitude loop, the Flag is set when the adjusting capacity of the inverter reaches the upper limit and the lower limit, and when the photovoltaic direct current converter detects the Flag of the inverter, the upper limit amplitude loop of the voltage of the second battery is triggered to take effect automatically.
Further, the working process of the second battery voltage upper limit limiting loop is as follows: the battery voltage upper limit amplitude limiting UbatUpLimit and the corresponding battery voltage feedback value UbatFb are subjected to difference and then sent to the PI controller, the output of the PI controller passes through an amplitude limiting loop and is inverted to be used as a voltage adjustment quantity delta UpvRef2, and the power of the photovoltaic battery is automatically adjusted by adjusting the MPPT output voltage reference value Upv0Ref of the photovoltaic maximum power tracking module to the open-circuit voltage so as to realize the adjustment of the charging power of the battery.
Further, the working process of the bus voltage upper limit amplitude limiting loop is as follows: the method comprises the steps that a photovoltaic direct current converter sets a bus voltage upper limit amplitude limiting value UbusUpLimit, the photovoltaic direct current converter obtains a bus voltage Ubus, the bus voltage upper limit amplitude limiting value UbusUpLimit and the bus voltage Ubus are input into a PI controller to be operated, amplitude limiting is carried out on the output result of the PI controller, and after the output result of the PI controller is negated, a value is assigned to a voltage adjustment quantity delta UpvRef.
Compared with the prior art, the invention has the advantages that: the invention starts from the control loop of the inverter and the photovoltaic direct current converter, automatically adjusts the power control of the inverter and the photovoltaic direct current converter by adding an additional control constraint loop, solves the problems of power distribution and safety constraint among power modules of the energy storage system, improves the dynamic response speed of the system and reduces the complexity of system control by replacing the power balance calculation of the system with the control constraint loop.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a topology diagram of a prior art energy storage system.
FIG. 2 is a typical dual loop control block diagram.
Fig. 3 is a flow chart of an implementation of the present invention.
FIG. 4 is a logic diagram of a specific implementation of the present invention.
Fig. 5 is a loop diagram of the inverter grid-connection control in the present invention.
Fig. 6 is a control loop diagram of the photovoltaic dc converter in the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the scope of the present invention will be more clearly and clearly defined.
A typical dual-loop control frame of the energy storage system is shown in other 2, an outer-loop given Rref(s) 201 and an outer-loop feedback RFb(s) 202 are differentiated and then sent to an outer-loop PI controller 203, the output of the PI controller is used as an inner-loop given after passing through an amplitude limiting link 205, the inner-loop given and an inner-loop feedback IFb(s) 205 are differentiated and then sent to an inner-loop PI controller 206, and the output of the inner-loop PI controller plus a feed-Forward value Forward(s) 207 is used as a power device duty ratio PWM output 208. Wherein the transfer function of the PI controller (203, 206) is f(s) = (kp s + ki)/s.
The control loop of the battery direct current converter is controlled by a bus voltage outer ring battery current inner ring double ring, the control target is to control the bus voltage given UbusRef at a constant value, therefore, the UbusRef is used as the input of a voltage loop, the voltage loop feeds back the bus voltage UbusFb, the voltage loop PI controller outputs the voltage loop PI controller divided by the number x of the online batteries as the given Ibatref of each circuit of battery current inner ring, the current inner ring feeds back the battery current IbatFb, and the feedforward value is the bus given value UbusRef. The upper limit of the limiting ring is the maximum allowable discharge current value of the battery, and the lower limit of the limiting ring is the maximum allowable charge current value of the battery.
The inverter grid-connected control loop is divided into grid-connected operation control and off-grid operation control, wherein the grid-connected operation control is controlled by double loops of an outer loop inversion current inner loop of inversion output power, and the control target is to accurately output an inversion output power given value Pinv0Ref, so that the Pinv0Ref is used as the input of the power loop, the power loop feeds back the inverter output power Pinvfb, the current inner loop feeds back the inversion current Iinvfb, and the feedforward value is the grid voltage Vgrid. The off-grid control is carried out by controlling an outer ring of the inversion output voltage and an inner ring of the inversion current, and the control target is to accurately output the inversion voltage given VinvRef, so that VinvRef is used as the input of the voltage outer ring, the voltage ring feeds back the output voltage VinvFb of the inverter, the current inner ring feeds back the inversion current IiinvFb, and the feedforward value is the inversion voltage given VinvRef.
The photovoltaic direct current converter control loop is controlled by a photovoltaic cell voltage outer loop photovoltaic cell current inner loop double loop, the control target is to control the photovoltaic cell voltage given UpvRef at the maximum power point MPPT of the photovoltaic cell, therefore, the UpvRef is used as the input of a voltage loop, the voltage loop feeds back the photovoltaic cell voltage UpvFb, the current inner loop feeds back the photovoltaic cell current IpvFb, and the feedforward value is the photovoltaic cell voltage given UpvRef.
Referring to fig. 3, 5 and 6, the invention discloses an energy storage system, which comprises an inverter grid-connected control loop and a photovoltaic direct current converter control loop, wherein the inverter grid-connected control loop is provided with a first battery voltage upper limit amplitude limiting loop 401 and a battery voltage lower limit amplitude limiting loop 402, and the photovoltaic direct current converter control loop is provided with a second battery voltage upper limit amplitude limiting loop 501 and a bus voltage upper limit amplitude limiting loop 502; by detecting the upper limit and the lower limit of the battery voltage and the upper limit of the bus voltage, the first battery voltage upper limit amplitude limiting loop 401, the battery voltage lower limit amplitude limiting loop 402, the second battery voltage upper limit amplitude limiting loop 501 and the bus voltage upper limit amplitude limiting loop 502 are automatically switched according to the operation mode judgment and detection results of the energy storage system, and the output power of the inverter and the photovoltaic direct-current converter is adjusted according to the loop results, so that the safety of the charging and discharging power of the battery is guaranteed.
Referring to fig. 4, the present invention also provides a control method of the energy storage system according to the above, the control method comprising the steps of,
and S301, judging the operation mode of the energy storage system.
And step S302, if the operation mode of the energy storage system is grid-connected operation, executing step S303.
In step S303, the energy storage system determines whether the battery voltage is limited to the upper limit, if so, step S304 is executed, otherwise, step S309 is executed.
Step S304, the first battery voltage upper limit limiting loop 401 is triggered to take effect automatically.
In step S305, the first battery voltage upper limit clipping loop 401 controls the battery voltage within the upper limit clipping by increasing the inverter discharge power or decreasing the inverter charge power.
And S306, judging the upper limit of the limiting value of the trigger power of the inverter by the energy storage system.
Step S307, the second battery voltage upper limit limiter loop 501 is triggered to take effect automatically.
In step S308, the second battery voltage upper limit limiting loop 501 controls the battery voltage within the upper limit limiting by reducing the output power of the photovoltaic dc converter.
In step S309, the energy storage system determines that the battery voltage reaches the lower limit.
In step S310, the battery voltage lower limit limiting loop 402 is triggered to take effect.
In step S311, the battery voltage lower limit limiting loop 402 controls the battery voltage above the lower limit by reducing the inverter discharge power or increasing the inverter charge power.
Step S312, if the operation mode of the energy storage system is off-grid operation, step S313 is executed.
In step S313, the energy storage system determines whether the battery voltage reaches an upper limit, if so, step S314 is executed, otherwise, step S316 is executed.
Step S314, triggering the second battery upper limit limiting loop 501 to automatically take effect.
In step S315, the second battery voltage upper limit limiting loop 501 controls the battery voltage within the upper limit limiting by reducing the output power of the photovoltaic dc converter.
In step S316, the energy storage system determines that the bus voltage exceeds the control value.
In step S317, the bus voltage upper limit limiting loop 502 is triggered to take effect automatically.
In step S318, the bus voltage upper limit limiting loop 502 controls the bus voltage within the upper limit limiting by reducing the output power of the photovoltaic dc converter.
According to the invention, a first battery voltage upper limit amplitude limiting loop 401 and a battery voltage lower limit amplitude limiting loop 402 are added to an inverter grid-connected control loop, a second battery voltage upper limit amplitude limiting loop 501 is added to a photovoltaic direct current converter control loop, and the safe automatic control of the battery voltage is realized by the automatic switching-in and switching-out of the loops. When the inverter is operated in an off-grid mode, a bus voltage upper limit amplitude limiting loop 502 is added to a photovoltaic direct current converter control loop, and the automatic switching-in and switching-out of the loop is carried out to achieve safe automatic control over battery charging and discharging power.
Referring to fig. 5, which is a loop diagram of the inverter grid-connected control, it can be seen that the working process of the first battery voltage upper limit limiting loop 401 is as follows: and the battery voltage upper limit amplitude limiting UbatUpdLimit (411) and the corresponding battery voltage feedback value UbatFb (412) are subjected to difference and then are sent to a PI controller, and the output of the PI controller is subjected to an amplitude limiting loop 414 and is inverted 415 to be used as an adjustment quantity delta PinvRef2 (416) of the output power of the inverter. Analysis shows that when the battery voltage feedback value UbatFb is smaller than the battery voltage upper limit amplitude limiting ubatupplimit, the battery is in the voltage safety range, the loop difference making result is positive, the output is positive after passing through the PI controller, the forward amplitude limiting is 0 by the amplitude limiting ring, and the output power adjustment quantity delta PinvRef2 is 0, so that the loop does not take effect. When the battery voltage feedback value UbastFb is larger than the battery voltage upper limit amplitude limiting UbastUplimit, the battery is about to be overcharged, the difference result of the loop is negative at the moment, the output is negative after the loop passes through the PI controller, the negative amplitude limiting of the amplitude limiting ring is effective at the moment, and the output delta PinvRef2 is larger than 0 after the negation processing 415, so that the output power is increased or the charging power is reduced, and the battery is prevented from being overcharged.
The working process of the battery voltage lower limit limiting loop 402 is as follows: and the battery voltage lower limit amplitude limiting UbatDpLimit (421) and the corresponding battery voltage feedback value UbatFb (422) are subjected to difference and then sent to the PI controller, and the output of the PI controller passes through an amplitude limiting loop 424 and is inverted 425 to be used as the adjustment quantity delta Pinv _ ref1 (426) of the output power of the inverter. Analysis shows that when the battery voltage feedback value UbatFb is larger than the battery voltage lower limit amplitude limit ubatdlimit, the battery is in the voltage safety range, the loop subtraction result is negative at the moment, the output is negative after passing through the PI controller, the amplitude limiting ring limits the negative direction to 0 at the moment, and the output power adjustment quantity delta PinvRef1 is 0, so that the loop does not take effect. When the battery voltage feedback value UbastFb is smaller than the battery voltage upper limit amplitude limiting UbastDpLimit, the battery is about to be over-discharged, the loop difference making result is positive, the output is positive after passing through the PI controller, the forward amplitude limiting of the amplitude limiting ring is effective, and the output delta PinvRef1 is smaller than 0 after being subjected to negation processing 425, so that the output power or the charging power is reduced, and the over-discharge of the battery is prevented.
In this embodiment, the step S306 specifically includes: when the inverter detects that the total power of the inverter is given PinvRef to be equal to the upper limit amplitude of the loop of the power limit amplitude, the Flag bit Flag is set when the regulating capacity of the inverter reaches the upper limit and the lower limit, and when the photovoltaic direct current converter detects the Flag of the inverter, the second battery voltage upper limit amplitude limiting loop 501 is triggered to automatically take effect.
The working process of the second battery voltage upper limit amplitude limiting loop 501 is consistent with that of the inverter battery voltage upper limit amplitude limiting loop (401), namely the battery voltage upper limit amplitude limiting UbatUpdLimit and the corresponding battery voltage feedback value UbatFb are subjected to difference and then sent to the PI controller, the output of the PI controller is subjected to the amplitude limiting loop and is inverted to be used as a voltage adjustment quantity delta UpvRef2 (511), and the photovoltaic maximum power tracking module MPPT (512) outputs a voltage reference value Upv0Ref (513) to be adjusted towards open-circuit voltage, so that the power of the photovoltaic battery is automatically adjusted, and the adjustment of the battery charging power is realized.
Referring to fig. 6, when the photovoltaic dc converter control loop and the photovoltaic dc converter operate at the maximum photovoltaic power point, it is detected that the bus voltage is higher than the target bus voltage value controlled by the battery dc converter, for example, ubusRef +20V, which indicates that the power between the power modules of the energy storage system is imbalanced, and at this time, the bus voltage upper limit limiting loop needs to be put into to adjust the output power of the photovoltaic dc converter, so as to maintain the system stable. The bus voltage upper limit limiting loop is designed to set a bus voltage upper limit limiting value UbusUpLimit, such as UbusUpLimit = UbusRef +20V, for the photovoltaic dc converter. The method comprises the steps that a photovoltaic direct-current converter obtains bus voltage Ubus, a bus voltage upper limit amplitude limiting value UbusUpLimit and the bus voltage Ubus are input into a PI controller to be operated, and amplitude limiting is carried out on output results of the PI controller, wherein positive amplitude limiting is 0, negative amplitude limiting is-700V, after the PI output results are inverted, delta UpvRef is assigned, and therefore when the photovoltaic direct-current converter detects that the bus voltage is larger than the bus voltage upper limit amplitude limiting value, the photovoltaic power is indicated to be too large, the PI output result delta UpvRef is larger than 0, namely the photovoltaic direct-current converter searches voltage and adjusts towards the photovoltaic open-circuit voltage direction to reduce the power output of the photovoltaic direct-current converter. When the bus voltage is smaller than the bus voltage upper limit amplitude limit, the photovoltaic power is in a normal range, and at the moment, the PI output result delta UpvRef is smaller than 0 and is limited to 0 by the amplitude limit ring, namely the output power of the photovoltaic direct current converter is not influenced.
The invention starts from the control loops of the inverter and the photovoltaic direct current converter, automatically adjusts the power control of the inverter and the photovoltaic direct current converter by adding an additional control constraint loop, solves the problems of power distribution and safety constraint among power modules of the energy storage system, and improves the dynamic response speed of the system and reduces the complexity of system control by replacing the power balance calculation of the system with the control constraint loop.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, various changes or modifications can be made by the owner within the scope of the appended claims, and the scope of the present invention should be covered by the owner as long as the protection scope of the present invention is not exceeded by the claims.
Claims (7)
1. The energy storage system comprises an inverter grid-connected control loop and a photovoltaic direct-current converter control loop, and is characterized in that the inverter grid-connected control loop is provided with a first battery voltage upper limit amplitude limiting loop and a battery voltage lower limit amplitude limiting loop, and the photovoltaic direct-current converter control loop is provided with a second battery voltage upper limit amplitude limiting loop and a bus voltage upper limit amplitude limiting loop; the method comprises the steps of automatically switching a first battery voltage upper limit amplitude limiting loop, a battery voltage lower limit amplitude limiting loop, a second battery voltage upper limit amplitude limiting loop and a bus voltage upper limit amplitude limiting loop according to the operation mode judgment and detection results of an energy storage system by detecting the upper limit and the lower limit of the battery voltage and the upper limit of the bus voltage, and adjusting the output power of an inverter and a photovoltaic direct current converter according to the loop results.
2. The control method of the energy storage system according to claim 1, characterized in that: comprises the following steps of (a) carrying out,
step S301, judging the operation mode of the energy storage system;
step S302, if the operation mode of the energy storage system is grid-connected operation, step S303 is executed;
step S303, the energy storage system judges whether the battery voltage is limited to the upper limit, if so, step S304 is executed, otherwise, step S309 is executed;
step S304, triggering a first battery voltage upper limit amplitude limiting loop to automatically take effect;
step S305, the first battery voltage upper limit amplitude limiting loop controls the battery voltage within the upper limit amplitude limit by increasing the discharge power of the inverter or decreasing the charge power of the inverter;
step S306, the energy storage system judges the upper limit of the limiting value of the trigger power of the inverter;
step S307, triggering a second battery voltage upper limit amplitude limiting loop to automatically take effect;
step S308, the second battery voltage upper limit amplitude limiting loop controls the battery voltage within the upper limit amplitude limit by reducing the output power of the photovoltaic direct-current converter;
step S309, the energy storage system judges that the battery voltage reaches the lower limit amplitude limit;
step S310, triggering a battery voltage lower limit limiting loop to take effect;
step S311, the battery voltage lower limit limiting loop controls the battery voltage above the lower limit limiting by reducing the discharge power of the inverter or increasing the charging power of the inverter;
step S312, if the operation mode of the energy storage system is off-grid operation, executing step S313;
step 313, the energy storage system determines whether the battery voltage reaches an upper limit amplitude limit, if so, step 314 is executed, otherwise, step 316 is executed;
step S314, triggering a second battery voltage upper limit amplitude limiting loop to automatically take effect;
step S315, the second battery voltage upper limit amplitude limiting loop controls the battery voltage within the upper limit amplitude limit by reducing the output power of the photovoltaic direct current converter;
step S316, the energy storage system judges that the bus voltage exceeds a control value;
step S317, triggering the bus voltage upper limit amplitude limiting loop to automatically take effect;
in step S318, the bus voltage upper limit limiting loop controls the bus voltage within the upper limit limiting by reducing the output power of the photovoltaic dc converter.
3. The control method of claim 2, wherein the first battery voltage upper limit limiting loop operates by: and the difference between the upper limit amplitude limit UbatUpLimit of the battery voltage and the corresponding battery voltage feedback value UbatFb is sent to the PI controller, and the output of the PI controller is subjected to an amplitude limiting loop and is inverted to be used as the adjustment quantity delta PinvRef2 of the output power of the inverter.
4. The control method according to claim 2, wherein the battery voltage lower limit clipping loop operates as follows: and the difference between the battery voltage lower limit amplitude limiting UbatDpLimit and the corresponding battery voltage feedback value UbatFb is sent to the PI controller, and the output of the PI controller is used as the adjustment quantity delta Pinv _ ref1 of the output power of the inverter after passing through an amplitude limiting loop and being inverted.
5. The control method according to claim 2, wherein the step S306 specifically includes: when the inverter detects that the total power of the inverter is given as PinvRef and is equal to the upper limit amplitude of the power limit amplitude loop, the Flag is set when the adjusting capacity of the inverter reaches the upper limit and the lower limit, and when the photovoltaic direct current converter detects the inverter Flag, the second battery voltage upper limit amplitude loop 501 is triggered to take effect automatically.
6. The control method according to claim 2 or 5, wherein the second battery voltage upper limit limiting loop operates by: and the difference between the battery voltage upper limit amplitude limiting UbatUpLimit and the corresponding battery voltage feedback value UbatFb is sent to a PI controller, the output of the PI controller passes through an amplitude limiting loop and is inverted to be used as a voltage adjustment quantity delta UpvRef2, and the power of the photovoltaic battery is automatically adjusted by adjusting the output voltage reference value Upv0Ref of the MPPT maximum power tracking module to the open-circuit voltage so as to realize the adjustment of the charging power of the battery.
7. The control method according to claim 2, wherein the bus voltage upper limit limiting loop operates by: the photovoltaic direct current converter sets a bus voltage upper limit amplitude limiting value UbusUpLimit, acquires a bus voltage Ubus, inputs the bus voltage upper limit amplitude limiting value UbusUpLimit and the bus voltage Ubus into a PI controller for operation, limits the amplitude of the output result of the PI controller, and assigns a voltage adjustment quantity delta UpvRef after negating the output result of the PI controller.
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